Image sensor based autonomous landing

ABSTRACT

A computer-implemented method of controlling an aircraft during autonomous landing. The method includes using a computer for performing the following: applying image processing on an image captured by a camera on board the aircraft while approaching a runway for identifying in the image a touchdown point (TDP) of the runway; calculating a deviation, in image parameters, of the TDP relative to the center of the image; converting the deviation in image parameters to angular and distance deviation values based on predefined ratios; calculating an offset of the aircraft&#39;s position relative to a landing corridor ending at the identified TDP based on the calculated angular and distance deviation; and transmitting the calculated offset to an aircraft control system configured to provide instructions for controlling the aircraft; wherein the offset is used for controlling the aircraft for guiding the aircraft towards the landing corridor to enable landing.

TECHNICAL FIELD

The presently disclosed subject matter relates to systems and methods ofcontrolling an aircraft during autonomous landing.

BACKGROUND

Unmanned aerial vehicles (UAVs), also known as, “drones”, can operatewith various degrees of autonomy: either under remote control by a humanoperator, or fully or intermittently autonomously, e.g., by on-boardcomputers. When operating a UAV remotely, datalink latency can makemanual control difficult or even dangerous during landing. Therefore,even in situations where the drone is normally operated by a human,autonomous landing can be used. Autonomous landing can also be used forlanding manned aircraft to help prevent accidents resulting from humanerror, for example, when there are poor flying conditions.

GENERAL DESCRIPTION

In many cases autonomous landing systems rely upon a Global PositioningSystem (GPS) in order to provide the location of the aircraft. However,in some circumstances GPS may be unavailable, for example, due tomalfunction or jamming. Therefore it is desirable to have a method andsystem for facilitating autonomous landing that is not dependent uponGPS.

According to one aspect of the presently disclosed subject matter thereis provided a computer-implemented method of controlling an aircraftduring autonomous landing. The method includes using a computer forperforming the following: applying image processing on an image capturedby a camera on-board the aircraft while approaching a runway foridentifying in the image a touchdown point (TDP) of the runway;calculating a deviation, in image parameters, of the TDP relative to thecenter of the image; converting the deviation in image parameters toangular and distance deviation values based on predefined ratios;calculating an offset of the aircraft's position relative to a landingcorridor ending at the identified TDP based on the calculated angularand distance deviation; and transmitting the calculated offset to anaircraft control system configured to provide instructions forcontrolling the aircraft; wherein the offset is used for controlling theaircraft for guiding the aircraft towards the landing corridor to enablelanding.

In addition to the above features, the method according to this aspectof the presently disclosed subject matter can include one or more offeatures (i) to (xi) listed below, in any desired combination orpermutation which is technically possible:

-   (i). wherein calculating a deviation in image parameters includes:    defining a horizontal y-axis and a vertical z-axis in the image, the    horizontal y-axis and the vertical z-axis intersecting through a    point of the image; calculating the lateral deviation in pixels from    the horizontal y-axis of the image to the identified TDP in the    image; and calculating the longitudinal deviation in pixels from the    vertical z-axis of the image to the identified TDP in the image.-   (ii). wherein calculating an offset of the aircraft's position    relative to a landing corridor includes: calculating the lateral    offset of the aircraft relative to the landing corridor; and    calculating the longitudinal offset of the aircraft relative to the    landing corridor.-   (iii). controlling the aircraft to guide the aircraft towards the    landing corridor.-   (iv). obtaining one or more aircraft parameters; and calculating the    offset of the aircraft's position relative to the landing corridor    also using the obtained one or more aircraft parameters.-   (v). obtaining one or more camera parameters of the camera's    positioning on-board the aircraft relative to an axis of the    aircraft; and calculating the offset of the aircraft's position    relative to the landing corridor also using the obtained one or more    camera parameters.-   (vi). repeating the process iteratively until the aircraft safely    lands.-   (vii). continuously obtaining images until a TDP is identified.-   (viii). wherein identifying in the image a TDP of the runway    includes: locating a runway in the image; identifying a beginning    and an ending of the runway; and identifying the location of the TDP    relative to the beginning and ending of the runway.-   (ix). wherein the one or more air parameters comprise one or more    of: an altitude of the aircraft from the ground; and an angle of the    aircraft.-   (x). wherein the aircraft is an unmanned aerial vehicle (UAV)-   (xi). wherein the field of view (FOV) of the camera is pointing in a    direction which allows capturing images of the area in front of the    aircraft's nose.

According to another aspect of the presently disclosed subject matterthere is provided a non-transitory program storage device readable bymachine, tangibly embodying a program of instructions executable by themachine to perform the above method of operating a sensor network.

This aspect of the disclosed subject matter can optionally include oneor more of features (i) to (xi) listed above, mutatis mutandis, in anydesired combination or permutation which is technically possible.

According to another aspect of the presently disclosed subject matterthere is provided a system mountable on an aircraft for controlling theaircraft during autonomous landing. The system includes a camera, and aprocessor operatively connected to the camera and configured to performthe following: obtain from the camera a captured image; identify in theimage a touchdown point (TDP) of the runway; calculate a deviation inimage parameters from the center of the image relative to the identifiedTDP; convert the deviation in image parameters to angular and distancedeviation based on predefined ratios; calculate an offset of theaircraft's position relative to a landing corridor ending at theidentified TDP based on the calculated angular and distance deviation;and transmit the calculated offset to an aircraft control systemconfigured to provide instructions for controlling the aircraft; whereinthe offset is used to control the aircraft during landing.

This aspect of the disclosed subject matter can optionally include oneor more of features (i) to (xi) listed above, mutatis mutandis, in anydesired combination or permutation which is technically possible. Inaddition to the above features, the system according to this aspect ofthe presently disclosed subject matter can include one or more offeatures (xii) to (xvi) listed below, in any desired combination orpermutation which is technically possible:

-   (xii). wherein the camera is selected from a group comprising of: a    panoramic camera; a mid-wavelength infrared camera; a short    wavelength infrared camera; a light detection and ranging camera;    and a synthetic aperture radar camera.-   (xiii). wherein the flight control system is operatively connected    to one or more of the group comprising of: an engine; a flight    control surface; and a landing gear.-   (xiv). wherein the one or more aircraft parameter sensors are    selected from a group comprising of: an altitude sensor; an angles    sensor; and a speed sensor.-   (xv). wherein the altitude sensor is selected from a group    comprising of: an altimeter; a radar altimeter; and a barometer.-   (xvi). wherein the angles sensor is selected from a group comprising    of: an inertial navigation system; a gyroscope; a compass; and a    magnetometer.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it can be carriedout in practice, embodiments will be described, by way of non-limitingexamples, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a functional block diagram of a system forcontrolling an aircraft during autonomous landing in accordance withcertain examples of the presently disclosed subject matter:

FIG. 2 illustrates a generalized flow-chart of a method for controllingan aircraft during autonomous landing in accordance with certainexamples of the presently disclosed subject matter;

FIG. 3 illustrates a flow-chart of a method for calculating imageparameter deviation in accordance with certain examples of the presentlydisclosed subject matter;

FIG. 4 illustrates schematically an image taken by a camera on-board theaircraft in accordance with certain examples of the presently disclosedsubject matter;

FIG. 5 illustrates a flow-chart of a method for calculating the offsetsof the aircraft's position relative to a landing corridor in accordancewith certain examples of the presently disclosed subject matter; and

FIG. 6 illustrates schematically a field of view of an image sensor inaccordance with certain examples of the presently disclosed subjectmatter.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresently disclosed subject matter may be practiced without thesespecific details. In other instances, well-known methods, procedures,components and circuits have not been described in detail so as not toobscure the presently disclosed subject matter.

Unless specifically stated otherwise, as apparent from the followingdiscussions, it is appreciated that throughout the specificationdiscussions utilizing terms such as “obtaining”, “identifying”,“calculating”. “converting”, “transmitting”, “defining”, “using”,“controlling”, “repeating”, “locating”. “generating”. “determining”, orthe like, refer to the action(s) and/or process(es) of a computer thatmanipulate and/or transform data into other data, said data representedas physical, such as electronic, quantities and/or said datarepresenting the physical objects.

The term “computer” or “processor” or variations thereof should beexpansively construed to cover any kind of hardware-based electronicdevice comprising a processing circuitry providing data processingcapabilities including, by way of non-limiting example a processingdevice (e.g. digital signal processor (DSP), microcontroller, fieldprogrammable circuit, application-specific integrated circuit (ASIC),etc.) or a device which comprises or is operatively connected to one ormore processing devices.

The operations in accordance with the teachings herein may be performedby a computer specially constructed for the desired purposes or by ageneral-purpose computer specially configured for the desired purpose bya computer program stored in a non-transitory computer-readable storagemedium.

Embodiments of the presently disclosed subject matter are not describedwith reference to any particular programming language. It will beappreciated that a variety of programming languages may be used toimplement the teachings of the presently disclosed subject matter asdescribed herein.

Bearing this in mind, attention is drawn to FIG. 1 illustrating anautonomous landing system 100 in accordance with certain examples of thepresently disclosed subject matter. The illustrated autonomous landingsystem 100 includes one or more processors 102 configured to performimage processing and execute various operations as disclosed herein.

Processor 102 is operatively connected to an image sensor 104, analtitude sensor 106, an angles sensor 108, a speed sensor 110, and anautomatic landing module (ALM) 112.

Image sensor 104 is located on-board an aircraft and its field of viewis pointing in a direction which allows capturing images of the area infront of the aircraft's nose. Image sensor 104 can include, for example,one or more of the following cameras/sensors: panoramic [pano], infrared[IR], mid-wavelength infrared [MWIR], short-wavelength infrared [SWIR],light detection and ranging [LIDAR], synthetic aperture radar [SAR], anyother appropriate multiple spectral sensing device that can be used as asensor during the daytime and/or night-time, etc. Optionally, imagesensor 104 can have different selectable modes of operation. Anappropriate mode of operation of the image sensor 104 can be selectedbased on various real-time parameters including for example, time ofday, weather, etc.

Altitude sensor 106 is configured to determine an altitude of theaircraft. Altitude sensor 106 can include, for example, one or more ofthe following sensors; altimeter, radar altimeter [RALT], barometer, orany other appropriate altitude sensing device.

Angles sensor 108 is configured to determine the angles of the aircraft(e.g. Euler angles, azimuth, etc.). Angles sensor 108 can include, forexample, one or more of the following types of sensors: inertialnavigation system [INS], gyroscope, compass, magnetometer, any otherappropriate angles sensing device, etc.

Speed sensor 110 is configured to sense a speed of the aircraft. Speedsensor 110 can include, for example, pitot tubes, or any otherappropriate speed sensing device.

Altitude sensor 106, angles sensor 108, and speed sensor 110 can bemounted on-board the aircraft.

ALM 112 can be located on-board the aircraft and is an aircraft controlsystem operatively connected to flight control systems 114 of theaircraft. ALM 112 is configured to receive data (e.g. from processor102) and control the landing of the aircraft accordingly. For example,ALM 112 can control the landing of the aircraft by generating flightcommands/instructions that are used by one or more of the flight controlsystems 114. ALM 112 can be, for example, an automatic take-off andlanding (ATOL) system.

Typical ATOL systems can provide automatic takeoff and landing utilizingDifferential Global Positioning System (DGPS) and Optronic Positioningand Tracking System (OPATS) based on ground laser radar and on-boardretro reflector.

In typical ATOL control loops, the UAV uses the position measurements tocalculate the deviation of the UAV from the Glide Slope (GLS). The UAVuses the ATOL control loops to maintain the GLS and runway centre line.All loops commands (pitch, roll, throttle, rudders, nose wheel steering)are calculated in accordance with the UAV status in the relevant process(takeoff or landing). The longitudinal loop controls the UAV's verticalposition relative to the desired GLS, the rate of descent and theattitude at touchdown. The lateral directional loops control theposition relative to the runway center line and perform runway steering.The loops ensure touchdown at proper heading and bank angles. When atypical ATOL system utilizes DGPS, lateral and vertical distancedeviations or “offsets” from the GLS are input to the ATOL system.

In a typical ATOL, the Optronic Positioning and Tracking System (OPATS)is a combined dual laser radar and TV camera sensor, measuring UAVdynamic positions during the takeoff or landing approach. The UAV is“lighted” by laser pulses from the laser radar. These pulses are echoedby the UAV retro reflector back to OPATS. From these echoes the OPATSdetermines UAV distance, azimuth, and elevation angle. This data istransferred to the UAV control System (UCS) and from the UCS to the UAVfor ATOL control loops feedback. Similar functionality can be achievedwith electromagnetic radar, using a ground-based transmitter and anairborne echo system.

The present invention can make use of an ATOL system, without the needof using a GPS or laser radar, by determining data from an imagecaptured by an image sensor as described herein below.

The present invention is also not reliant upon radar transmissions thatare sent from ground-based radar transmitters, and, thus does notrequire that such ground based radar transmitters be deployed andpresent at each of the landing sites.

Flight control systems 114 are operatively connected to varioussubsystems on-board the aircraft configured to enable maneuvering theaircraft. These subsystems can include, for example: engine 116, flightcontrol devices 118 (e.g., ailerons, elevator, rudder, spoilers, flaps,slats, air brakes, etc.), landing gear 120, etc.

It is noted that the teachings of the presently disclosed subject matterare not bound by autonomous landing system 100 described with referenceto FIG. 1. Equivalent and/or modified functionality can be consolidatedor divided in another manner and can be implemented in any appropriatecombination of software with firmware and/or hardware and executed on asuitable device. For example, images can be provided by other systems,including third party equipment, and processing can be done remotelyfrom the aircraft.

Reference is now made to FIGS. 2, 3, and 5 which show flow charts ofoperations in accordance with certain examples of the presentlydisclosed subject matter.

It is noted that the teachings of the presently disclosed subject matterare not bound by the flow charts illustrated in FIGS. 2, 3, and 5, and,the illustrated operations can occur out of the illustrated order. Forexample, operations 306 and 308 shown in succession can be executedsubstantially concurrently or in the reverse order. It is also notedthat whilst the flow charts are described with reference to elements ofautonomous landing system 100, this is done by way of example only andshould not be construed as limiting.

FIG. 2 illustrates a generalized flow-chart of a method for controllingan aircraft during autonomous landing in accordance with certainexamples of the presently disclosed subject matter.

At block 202, parameters relating to a landing corridor relative to atouchdown point (TDP) are defined and/or obtained (e.g., by processor102). The term, “touchdown point”, as used herein, refers to an area ofa runway which is suitable for commencing the landing of the aircraft onthe runway thereon (for example a designated area for initial touchdownof the aircraft on the runway). The location of the TDP relative to therunway can be different for different types of airborne platforms.

The term, “landing corridor”, as used herein, refers to a flight pathfor leading the aircraft to the TDP during landing. The landing corridorprovides a reference for the aircraft to use as guidance when landing.As such, the landing corridor can include various lateral, longitudinal,altitudinal, and angular parameters, defining its position and coursewith respect to the TDP and/or runway. The parameters of the landingcorridor can be predefined and stored in a memory of the system, forobtaining by the processor when requested.

The landing corridor can comprise one or more gliding legs extendingover different distances and in different angles. In one, non-limiting,example, the landing corridor can comprise a 400 meter glide path with a1.5° incline originating at the TDP, followed by a 3 kilometer glidepath with a 4° incline. In another, non-limiting, example, the TDP canbe predefined as being located at the end of the first third of therunway, and the landing corridor can be defined as a glide path with a1.5° incline from the TDP backward for 300 meters, followed by a glidepath with a 4° incline for 2 kilometers.

At block 204 one or more camera parameters are defined and/or obtained(e.g., by processor 102). The camera parameters can be predefined andstored in a memory of the system, for obtaining by the processor whenrequested. Camera parameters include, but are not limited to, angle ofview of the camera, bearing and depression angles of the camera relativeto the aircraft's axes, field of view (FOV) of the camera, etc.

In some cases these camera parameters can be constant, for example, ifthe camera is attached to the aircraft in a fixed position (e.g.,substantially straight ahead with a relatively small tilt downwards). Inother cases these camera parameters need to be constantly updated basedon the current position of the camera, for example, where the camera isattached to the aircraft using a rotatable support, such as a gimbal.

In some cases, even when the camera is attached at a fixed position, thefield of view can be affected by a mode of operation of the camera(e.g., zoom in, or zoom out).

At block 206 one or more aircraft parameters are determined (e.g., byaltitude sensor 106, angles sensor 108, speed sensor 110, etc.).Aircraft parameters include, but are not limited to, altitude of theaircraft, angular orientation of the aircraft, speed of the aircraft,etc.

At block 208 at least one image is captured (e.g., by image sensor 104),while the aircraft is approaching a runway. As mentioned above, thefield of view of image sensor 104 is fixed to the aircraft with its FOVpointing in a direction which allows capturing images of the area infront of the aircraft's nose. A schematic illustration demonstrating acamera attached to an aircraft and the FOV of an image sensor is shownin FIG. 6.

Image processing is applied to the captured image to identify the TDP ofthe runway (block 210). Optionally, a beginning and an ending of therunway can also be identified in the captured image, and the location ofthe TDP can be identified relative to the location of the beginning andending of the runway (e.g., the TDP is identified as being located atthe end of the first third of the runway).

In some examples, multiple images can be captured simultaneously frommultiple cameras in synchronization, each with the same and/or differentangular orientation but with an, at least partially, overlapping view ofthe TDP, and processing can be performed on each image of the set ofimages in order to obtain data redundancy and thereby increase therobustness of TDP identification. Optionally, if multiple cameras areused, different cameras can be configured to have different respectivespectral performance.

Once a TDP is identified in the image, image parameters of TDP-deviationfrom the center of the image are calculated (block 212). Imageparameters can include for example, image pixels, and the TDP deviationcan be defined by pixels. A more detailed example of this calculating isprovided below with reference to FIGS. 3 and 4.

The calculated image parameters defining the TDP-deviation can beconverted to angular and/or distance deviation (block 214). For example,image parameters can be converted based on a ratio, such as a pixel toangle ratio and/or a pixel to distance ratio (defining the value inangles of each pixel or the value in meters of each pixel in the captureimage).

When converting image parameters to angular and distance deviation, thecamera's FOV can be taken into account. For example, assuming that thewidth pixel dimension of the image is different than the height pixeldimension of the image, a first pixel to angle ratio for the horizontalaxis can be determined by dividing the number of pixels across the imagewidth by the FOV of the camera. A second pixel to angle ratio for thevertical axis can be determined by dividing the number of pixels acrossthe image height by the FOV of the camera. After the pixel to angleratio for each axis is determined, then the horizontal deviation of theTDP in pixels from the center of the image can be converted tohorizontal angular deviation using the pixel to angle ratio determinedfor the horizontal axis, and, the vertical deviation of the TDP inpixels from the center of the image can be converted to vertical angulardeviation using the pixel to angle ratio determined for the verticalaxis. In this example, after converting the pixels to angular deviationusing the FOV information, the distance deviation can be calculatedusing the angular deviation (e.g., also using angles of observation, andthe altitude of the aircraft relative to the ground).

The above calculations are done in real-time for progressive images thatare captured. Earlier values that were calculated in relation to anearlier image are different than later values that are calculated inrelation to a later image, since the calculations are based on thespecific characteristics of the image and the characteristics of anearlier image are different than the characteristics of a later image.The calculations for a later image are not dependent on the earlierimage. Since the position of the aircraft dictates the aircraft's viewof the TDP, the calculated values related to a particular image relateto the position of the aircraft when that particular image was obtained.For example, as the aircraft changes position between the time that eachprogressive image is captured, when a new, later image is captured theaircraft has a new, different distance from the TDP when that particularimage is captured, and thus a new, different view in relation to theTDP. Thus, that newly captured later image has new characteristics whichresult in new calculated values that are different than the previousvalues that were calculated based on a previously captured, earlierimage (which had a different view of the TDP).

The calculations for a particular time period are performed in relationto one particular current image or a related set of simultaneouslycaptured current images having similar, at least partially overlapping,characteristics of a particular scene (as related to above with regardto capturing multiple images in synchronization).

At block 216 the offset of the aircraft's position relative to thelanding corridor (ending at the TDP) is calculated. These calculationscan be based, on various parameters including, for example: the angularand distance deviation, the camera parameters, the aircraft parameters(e.g., altitude, attitude, speed, etc.), etc. A more detailed example ofthis calculating is provided below with reference to FIG. 5.

The calculated offsets are transmitted to ALM 112 to enable execution ofautomatic landing. The calculated offsets are used for controlling theaircraft to rectify the offsets in order to fly towards the landingcorridor and position the aircraft in the appropriate location forlanding. For example, responsive to receiving the calculated offsets.ALM 112 generates respective instructions, calculated based on theoffsets, and sends the instructions to the flight control systems 114.Flight control systems 114 in turn controls one or more of thesubsystems of the aircraft (e.g. engine 116 and/or flight controlsurfaces 118), based on the received flight commands, in order to guidethe aircraft towards the landing corridor.

The above process can be repeated in order to direct the aircraft moreaccurately towards the landing corridor until the aircraft can safelyland on the runway.

FIG. 3 illustrates a flow-chart of a method for calculating TDPdeviation in accordance with certain examples of the presently disclosedsubject matter. FIG. 3 is described with reference to FIG. 4 whichschematically illustrates an image 400 taken by image sensor 104on-board the aircraft in accordance with certain examples of thepresently disclosed subject matter.

As described above with reference to blocks (208)-(210) of FIG. 2, animage of a runway is received at the system to be processed. Forexample, processor 102 receives an image 400 captured by image sensor104 located on-board the aircraft. Processor 102 (e.g. with the help ofan image processing module operatively connected to the processor) canbe configured to process the received image and identify a TDP 404 inrunway 406.

As part of the processing of the image a horizontal axis (e.g. y-axis)and a vertical axis (e.g. z-axis) are defined in the image (block 304).The horizontal y-axis and the vertical z-axis intersect through a pointof the image. For example, processor 102 can be configured to processthe image and define the axes through a center point 402 in image 400.

Once the y and z axes are defined, the lateral distance of the TDPmeasured in pixels from the horizontal x-axis is calculated (block 306)as well as the longitudinal distance of the TDP measured in pixels fromthe vertical z-axis (block 308). For example, processor 102 can beconfigured to calculate the lateral distance in pixels Δy from thehorizontal y-axis Y and longitudinal distance in pixels Δz from thevertical z-axis Z to the identified TDP 404, as schematicallyillustrated in FIG. 4.

The calculated lateral distance and vertical distance is converted frompixel values to angular and distance values to thereby obtain theoffsets of the aircraft's position relative to the landing corridorending at the identified TDP, as described above with reference toblocks (214)-(216) of FIG. 2. A more detailed example of thiscalculation (216) is provided below with reference to FIG. 5.

FIG. 5 illustrates a flow-chart of a method for calculating the offsetsof the aircraft's position in accordance with certain examples of thepresently disclosed subject matter.

As described above with reference to blocks (202)-(206) and (214) ofFIG. 2, before commencing calculation of the aircraft's offset from thelanding corridor, the data needed for completing the calculation isobtained (block 502). The obtained data includes, for example, thecalculated angular and distance deviation, the parameters of the landingcorridor, one or more camera parameters, and one or more aircraftparameters (e.g. altitude, angles, speed, etc., of the aircraft). Atleast part of the data can be determined by various sensors onboard theaircraft, for example, altitude sensor 106, angles sensor 108, speedsensor 110, etc.

The lateral offset ΔY and longitudinal offset ΔZ with respect to thelanding corridor ending at the TDP is calculated (block 504). Thelateral offset ΔY and longitudinal offset ΔZ can be calculated using theangular and distance deviation and the various other parameters. Forexample, these calculations can be done using the altitude of theaircraft which is compared with the altitude parameters of the landingcorridor. A vector in earth axes which connects the camera location andthe TDP location can be calculated using the result of this comparisonalong with: the Euler angles of the aircraft (obtained, for example,from the onboard INS), the bearing and depression angles of the camera,and the angular offsets that were calculated earlier. As well known inthe art, the term, “vector in earth axes”, relates to a vector which itsaxes are absolute in relation to the Earth. Using this vector and thelanding corridor parameters, the lateral offset ΔY and the longitudinaloffset ΔZ can be extracted. These calculations can be done regardless ofthe wind effect, since these calculations take into account the aircraftEuler angles (including heading), the camera angular position relativeto the aircraft, and the angular deviation between the center of theimage and the location of the TDP in the image. Meaning, since theangular attitude of the aircraft is determined, the angular attitude ofthe image sensor is used to calculate the line of sight (LOS) vector inearth axes, and the aircraft location is calculated using the FOV andconversions mentioned above for calculating the distance deviations anddelivering them to aircraft control system (e.g. ATOL system). Thus,these calculations are not affected by the slide angle of the heading ofthe aircraft from the ground vector direction, which can be created bythe wind.

As mentioned above, the aircraft location relative to the TDP iscalculated. Then, using the parameters of the landing corridor, thedistance deviation of the aircraft from the landing corridor can becalculated.

Once the offsets have been calculated, the offsets can be used forguiding the aircraft towards the landing corridor to allow safe landing,as described above with reference to blocks (218)-(220) of FIG. 2. Forexample, processor 102 can be configured to transmit the offsets to ALM112, and ALM 112 can be configured in turn to generate instructionsdirected for controlling flight subsystems to enable guiding theaircraft towards the landing corridor.

It is to be understood that the invention is not limited in itsapplication to the details set forth in the description contained hereinor illustrated in the drawings. The invention is capable of otherexamples and of being practiced and carried out in various ways. Hence,it is to be understood that the phraseology and terminology employedherein are for the purpose of description and should not be regarded aslimiting. As such, those skilled in the art will appreciate that theconception upon which this disclosure is based may readily be utilizedas a basis for designing other structures, methods, and systems forcarrying out the several purposes of the presently disclosed subjectmatter.

It will also be understood that the system according to the inventionmay be, at least partly, implemented on a suitably programmed computer.Likewise, the invention contemplates a computer program being readableby a computer for executing the method of the invention. The inventionfurther contemplates a non-transitory computer-readable memory tangiblyembodying a program of instructions executable by the computer forexecuting the method of the invention.

Those skilled in the art will readily appreciate that variousmodifications and changes can be applied to the embodiments of theinvention as hereinbefore described without departing from its scope,defined in and by the appended claims.

1. A computer-implemented method of controlling an aircraft duringautonomous landing, comprising: using a computer for performing thefollowing: applying image processing on an image captured by a cameraon-board the aircraft while approaching a runway for identifying in theimage a touchdown point (TDP) of the runway; calculating a deviation, inimage parameters, of the TDP relative to the center of the image;converting the deviation in image parameters to angular and distancedeviation values based on predefined ratios; calculating an offset ofthe aircraft's position relative to a landing corridor ending at theidentified TDP based on the calculated angular and distance deviation;and transmitting the calculated offset to an aircraft control systemconfigured to provide instructions for controlling the aircraft; whereinthe offset is used for controlling the aircraft for guiding the aircrafttowards the landing corridor to enable landing.
 2. The computerizedmethod of claim 1, wherein calculating a deviation in image parametersincludes: defining a horizontal y-axis and a vertical z-axis in theimage, the horizontal y-axis and the vertical z-axis intersectingthrough a point of the image; calculating the lateral deviation inpixels from the horizontal y-axis of the image to the identified TDP inthe image; and calculating the longitudinal deviation in pixels from thevertical z-axis of the image to the identified TDP in the image.
 3. Thecomputerized method of any one of the preceding claims, whereincalculating an offset of the aircraft's position relative to a landingcorridor includes: calculating the lateral offset of the aircraftrelative to the landing corridor; and calculating the longitudinaloffset of the aircraft relative to the landing corridor.
 4. Thecomputerized method of any one of the preceding claims, furthercomprising: controlling the aircraft to guide the aircraft towards thelanding corridor.
 5. The computerized method of any one of the precedingclaims, further comprising: obtaining one or more aircraft parameters;and calculating the offset of the aircraft's position relative to thelanding corridor also using the obtained one or more aircraftparameters.
 6. The computerized method of any one of the precedingclaims, further comprising: obtaining one or more camera parameters ofthe camera's positioning on-board the aircraft relative to an axis ofthe aircraft; and calculating the offset of the aircraft's positionrelative to the landing corridor also using the obtained one or morecamera parameters.
 7. The computerized method of any one of thepreceding claims, further comprising: repeating the process iterativelyuntil the aircraft safely lands.
 8. The computerized method of any oneof the preceding claims, further comprising: continuously obtainingimages until a TDP is identified.
 9. The computerized method of any oneof the preceding claims, wherein identifying in the image a TDP of therunway includes: locating a runway in the image; identifying a beginningand an ending of the runway; and identifying the location of the TDPrelative to the beginning and ending of the runway.
 10. The computerizedmethod of any one of claims 5 to 9, wherein the one or more airparameters comprise one or more of: an altitude of the aircraft from theground; and an angle of the aircraft.
 11. The computerized method of anyone of the preceding claims, wherein the aircraft is an unmanned aerialvehicle (UAV).
 12. The computerized method of any one of the precedingclaims, wherein the field of view (FOV) of the camera is pointing in adirection which allows capturing images of the area in front of theaircraft's nose.
 13. A system mountable on an aircraft for controllingthe aircraft during autonomous landing, comprising: a camera; and aprocessor operatively connected to the camera and configured to performthe following: obtain from the camera a captured image; identify in theimage a touchdown point (TDP) of the runway; calculate a deviation inimage parameters from the center of the image relative to the identifiedTDP; convert the deviation in image parameters to angular and distancedeviation based on predefined ratios; calculate an offset of theaircraft's position relative to a landing corridor ending at theidentified TDP based on the calculated angular and distance deviation;and transmit the calculated offset to an aircraft control systemconfigured to provide instructions for controlling the aircraft; whereinthe offset is used to control the aircraft during landing.
 14. Thesystem of claim 13, wherein the processor is further configured to:define a horizontal y-axis and a vertical z-axis in the image, thehorizontal y-axis and the vertical z-axis intersecting through a pointof the image; calculate the lateral deviation in pixels from thehorizontal y-axis of the image to the identified TDP in the image; andcalculate the longitudinal deviation in pixels from the vertical z-axisof the image to the identified TDP in the image.
 15. The system of anyone of claims 13 to 14, wherein the processor is further configured to:calculate the lateral offset of the aircraft relative to the landingcorridor; and calculate the longitudinal offset of the aircraft relativeto the landing corridor.
 16. The system of any one of claims 13 to 15,further comprising: a flight control system for controlling the aircraftto guide the aircraft towards the landing corridor based on one or morecommands from the aircraft control system.
 17. The system of any one ofclaims 13 to 16, further comprising: one or more aircraft parametersensors for sensing an aircraft parameter; wherein the aircraftparameter is also used for calculating the offset of the aircraft'sposition relative to the landing corridor.
 18. The system of any one ofclaims 13 to 17, wherein the processor is further configured to: obtainone or more camera parameters of the camera's positioning on-board theaircraft relative to an axis of the aircraft; and calculate thedeviation in image parameters also using the obtained one or more cameraparameters.
 19. The system of any one of claims 13 to 18, wherein theprocessor is further configured to: repeat the process iteratively untilthe aircraft safely lands.
 20. The system of any one of claims 13 to 19,wherein the system is further configured to: continuously capture imagesuntil a TDP is identified.
 21. The system of any one of claims 13 to 20,wherein the processor is further configured to: locate a runway in theimage; identify a beginning and an ending of the runway; and identifythe location of the TDP relative to the beginning and ending of therunway.
 22. The system of any one of claims 13 to 21, wherein the camerais selected from a group comprising of: a panoramic camera; amid-wavelength infrared camera; a short-wavelength infrared camera; alight detection and ranging camera; and a synthetic aperture radarcamera.
 23. The system of any one of claims 13 to 22, wherein the flightcontrol system is operatively connected to one or more of the groupcomprising of: an engine; a flight control surface; and a landing gear.24. The system of any one of claims 17 to 23, wherein the one or moreaircraft parameter sensors are selected from a group comprising of: analtitude sensor; an angles sensor; and a speed sensor.
 25. The system ofclaim 24, wherein the altitude sensor is selected from a groupcomprising of: an altimeter; a radar altimeter; and a barometer.
 26. Thesystem of any one of claims 24 to 25, wherein the angles sensor isselected from a group comprising of: an inertial navigation system; agyroscope; a compass; and a magnetometer.
 27. The system of any one ofclaims 13 to 26, wherein the aircraft is an unmanned aerial vehicle(UAV).
 28. The system of any one of claims 13 to 27, wherein the fieldof view (FOV) of the camera is pointing in a direction which allowscapturing images of the area in front of the aircraft's nose.
 29. Anon-transitory program storage device readable by machine, tangiblyembodying a program of instructions executable by the machine to performa method of controlling an aircraft during autonomous landing,comprising: using a processor for performing the following: obtaining animage captured by a camera on-board the aircraft while approaching arunway; identifying in the image a touchdown point (TDP) of the runway;calculating a deviation in image parameters from the center of the imagerelative to the identified TDP; converting the deviation in imageparameters to angular and distance deviation based on predefined ratios;calculating an offset of the aircraft's position relative to a landingcorridor ending at the identified TDP based on the calculated angularand distance deviation; and transmitting the calculated offset to anaircraft control system configured to provide instructions forcontrolling the aircraft; wherein the offset is used for controlling theaircraft during landing.